Light emitting device

ABSTRACT

A light emitting device includes a light emitting unit, a light transmissive layer and an encapsulant. The light emitting unit includes a substrate, an epitaxial structure layer disposed on the substrate, and a first electrode and a second electrode disposed on the same side of the epitaxial structure layer, respectively. The light emitting unit is disposed on the light transmissive layer and at least a part of the first electrode and a part of the second electrode are exposed by the light transmissive layer. The encapsulant encapsulates the light emitting unit and at least exposes a part of the first electrode and a part of the second electrode. Each of the first electrode and the second electrode extends outward from the epitaxial structure layer, and covers at least a part of an upper surface of the encapsulant, respectively.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of and claims the priority benefit of U.S. application Ser. No. 15/405,323, filed on Jan. 13, 2017, now allowed. The prior U.S. application Ser. No. 15/405,323 is a continuation application of and claims the priority benefit of U.S. prior application Ser. No. 14/705,977, filed on May 7, 2015, now abandoned, which claims the priority benefit of Taiwan application serial no. 103116262, filed on May 7, 2014, Taiwan application serial no. 104113482, filed on Apr. 27, 2015, and Taiwan application serial no. 103116987, filed on May 14, 2014. The entirety of each of the above-mentioned patent applications is hereby incorporated by reference herein and made a part of this specification.

BACKGROUND OF THE INVENTION Field of the Invention

The invention relates to a light emitting device, and particularly relates to a light emitting diode (LED) package structure.

Description of Related Art

In a conventional flip-chip LED package structure, an edge of an epitaxial structure layer is aligned with or contracted inward relative to an edge of a substrate, and edges of an N electrode and a P electrode are aligned with the edge of the epitaxial structure layer or is spaced by a vertical distance with the edge of the epitaxial structure layer. Namely, an orthogonal projection area of the N electrode and the P electrode on the substrate is smaller than an orthogonal projection area of the epitaxial structure layer on the substrate. In case of such configuration, when the flip-chip LED package is to be assembled to an external circuit, since an electrode area of the N electrode and the P electrode is relative small, the LED package may have problems of inaccurate alignment and poor electrode contact in assembling.

SUMMARY OF THE INVENTION

The invention is directed to a light emitting device having a larger electrode area, which avails improving an alignment accuracy in follow-up assembling.

The invention provides a light emitting device including a light emitting unit, a light transmissive layer and an encapsulant. The light emitting unit includes a substrate, an epitaxial structure layer disposed on the substrate, and a first electrode and a second electrode respectively disposed on a same side of the epitaxial structure layer. The light emitting unit is disposed on the light transmissive layer and the light transmissive layer at least exposes the first electrode and the second electrode. The encapsulant encapsulates the light emitting unit and at least exposes a part of the first electrode and a part of the second electrode. The first electrode and the second electrode respectively extend outward from the epitaxial structure layer, and respectively cover at least a part of an upper surface of the encapsulant.

In an embodiment of the invention, the first electrode includes a first electrode portion connected to the epitaxial structure layer and a first electrode extending portion connected to the first electrode portion, and the second electrode includes a second electrode portion connected to the epitaxial structure layer and a second electrode extending portion connected to the second electrode portion, and the first electrode extending portion and the second electrode extending portion respectively extend outward to at least a part of the upper surface of the encapsulant.

In an embodiment of the invention, the first electrode extending portion and the second electrode extending portion are aligned with or contracted inward relative to an edge of the upper surface of the encapsulant.

In an embodiment of the invention, the first electrode portion and the second electrode portion are aligned with or contracted inward relative to an edge of the epitaxial structure layer.

In an embodiment of the invention, the light emitting device further includes one or a plurality of flat surfaces, and each of the flat surfaces includes the light transmissive layer and the encapsulant.

In an embodiment of the invention, the first electrode extending portion includes a plurality of first grating type electrodes, and the second electrode extending portion includes a plurality of second grating type electrodes, the first grating type electrodes are distributed on the first electrode portion and a part of the upper surface of the encapsulant, and the second grating type electrodes are distributed on the second electrode portion and a part of the upper surface of the encapsulant.

In an embodiment of the invention, at least a part of the first electrode extending portion extends from an edge of the first electrode portion towards a direction away from the second electrode portion, and at least a part of the second electrode extending portion extends from an edge of the second electrode portion towards a direction away from the first electrode portion.

In an embodiment of the invention, the first electrode extending portion and the second electrode extending portion respectively include a plurality of sub-electrodes separated from each other.

In an embodiment of the invention, the sub-electrodes of the first electrode extending portion are located in at least one corner away from the second electrode on the upper surface of the encapsulant, and the sub-electrodes of the second electrode extending portion are located in at least one corner away from the first electrode on the upper surface of the encapsulant.

In an embodiment of the invention, top surfaces of the first electrode extending portion and the second electrode extending portion are substantially coplanar with the upper surface of the encapsulant.

In an embodiment of the invention, the first electrode portion and the first electrode extending portion are seamlessly connected, and the second electrode portion and the second electrode extending portion are seamlessly connected.

In an embodiment of the invention, the first electrode extending portion and the second electrode extending portion respectively include an adhesion layer and a barrier layer disposed between the adhesion layer and the encapsulant.

In an embodiment of the invention, a material of the adhesion layer includes gold, tin, aluminium, silver, copper, indium, bismuth, platinum, gold-tin alloy, tin-silver alloy, tin-silver-copper alloy (Sn—Ag—Cu (SAC) alloy) or a combination thereof, and a material of the barrier layer includes nickel, titanium, tungsten, gold or an alloy of a combination thereof.

In an embodiment of the invention, the first electrode and the second electrode respectively include a reflection layer respectively disposed between the electrode extending portions and the encapsulant.

In an embodiment of the invention, a material of the reflection layer includes gold, aluminium, silver, nickel, titanium, or an alloy of a combination thereof.

In an embodiment of the invention, the light emitting device further includes a reflection layer, disposed on the upper surface of the encapsulant.

In an embodiment of the invention, at least a part of the reflection layer is located between the electrodes and the encapsulant.

In an embodiment of the invention, a material of the reflection layer includes gold, aluminium, silver, nickel, titanium, distributed Bragg reflector (DBR), a resin layer doped with reflection particles with high reflectivity or a combination thereof

In an embodiment of the invention, the light emitting device further includes a wavelength conversion material wrapping the light emitting unit and at least exposing a part of the first electrode and a part of the second electrode.

In an embodiment of the invention, the wavelength conversion material includes a fluorescent material or a quantum dot material.

In an embodiment of the invention, the wavelength conversion material is formed on a surface of the light emitting unit, formed on a surface of the encapsulant or mixed in the encapsulant.

In an embodiment of the invention, the first sub-electrodes and the second sub-electrodes are laminar electrodes, spherical electrodes, or grating type electrodes.

An embodiment of the invention provides a light emitting device including a light emitting unit, a light transmissive layer and an encapsulant. The light emitting unit includes a substrate, an epitaxial structure layer disposed on the substrate, and a first electrode and a second electrode respectively disposed on a same side of the epitaxial structure layer opposite to the substrate. The light transmissive layer is disposed on the light emitting unit and is located at one side of the substrate opposite to the epitaxial structure layer, the first electrode and the second electrode. The encapsulant is located between the light emitting unit and the light transmissive layer. The encapsulant encapsulates the light emitting unit and at least exposes a part of the first electrode and a part of the second electrode. The first electrode and the second electrode respectively extend outward from the epitaxial structure layer, and respectively cover at least a part of an upper surface of the encapsulant.

An embodiment of the invention provides a light emitting device including a light emitting unit and an encapsulant. The light emitting unit includes a substrate, an epitaxial structure layer disposed on the substrate, and a first electrode and a second electrode respectively disposed on a same side of the epitaxial structure layer. The encapsulant encapsulates the light emitting unit and at least exposes a part of the first electrode and a part of the second electrode. The first electrode and the second electrode respectively extend upward from the epitaxial structure layer without covering an upper surface of the encapsulant.

An embodiment of the invention provides a light emitting device including a light emitting unit and an encapsulant. The light emitting unit includes a substrate, an epitaxial structure layer disposed on the substrate, and a first electrode and a second electrode respectively disposed on a same side of the epitaxial structure layer. The encapsulant encapsulates the light emitting unit and at least exposes a part of the first electrode and a part of the second electrode. The first electrode and the second electrode respectively extend outward from the epitaxial structure layer and respectively cover at least a part of an upper surface of the encapsulant.

An embodiment of the invention provides a light emitting device including a light emitting unit, a light transmissive layer and an encapsulant. The light emitting unit includes a substrate, an epitaxial structure layer disposed on the substrate, and a first electrode and a second electrode respectively disposed on a same side of the epitaxial structure layer. The light emitting unit is disposed on the light transmissive layer and at least exposes the first electrode and the second electrode. The encapsulant encapsulates the light emitting unit and at least exposes a part of the first electrode and a part of the second electrode. The first electrode and the second electrode respectively extend upward from the epitaxial structure layer without covering an upper surface of the encapsulant.

An embodiment of the invention provides a light emitting device including a light emitting unit, a light transmissive layer and an encapsulant. The light emitting unit includes a substrate, an epitaxial structure layer disposed on the substrate, and a first electrode and a second electrode respectively disposed on a same side of the epitaxial structure layer opposite to the substrate. The light transmissive layer is disposed on the light emitting unit and is located at one side of the substrate opposite to the epitaxial structure layer, the first electrode and the second electrode. The encapsulant is located between the light emitting unit and the light transmissive layer, and encapsulates the light emitting unit and at least exposes a part of the first electrode and a part of the second electrode. The first electrode and the second electrode respectively extend upward from the epitaxial structure layer without covering an upper surface of the encapsulant.

According to the above descriptions, since the first electrode and the second electrode of the light emitting unit according to an embodiment of the invention extend outward from the epitaxial structure layer, and may cover at least a part of the encapsulant, compared to the conventional design of the first electrode and the second electrode, the light emitting device (the LED package) according to the embodiment of the invention has a larger electrode area, and when the light emitting device is to be assembled to an external circuit, the alignment accuracy of assembling is effectively improved. Since the first electrode and the second electrode of the light emitting unit according to an embodiment of the invention extend upward from the epitaxial structure layer, and protrude out of the encapsulant, it avails a follow-up chip bonding process.

In order to make the aforementioned and other features and advantages of the invention comprehensible, several exemplary embodiments accompanied with figures are described in detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

FIG. 1A is a top view of a light emitting diode (LED) package structure according to an embodiment of the invention.

FIG. 1B is a cross-sectional view of the LED package structure of FIG. 1A viewing along a line A-A.

FIG. 2A is a top view of an LED package structure according to another embodiment of the invention.

FIG. 2B is a cross-sectional view of the LED package structure of FIG. 2A viewing along a line B-B.

FIG. 3A is a top view of an LED package structure according to another embodiment of the invention.

FIG. 3B is a cross-sectional view of the LED package structure of FIG. 3A viewing along a line C-C.

FIG. 4A is a top view of an LED package structure according to another embodiment of the invention.

FIG. 4B is a cross-sectional view of the LED package structure of FIG. 4A viewing along a line D-D.

FIG. 5A is a top view of an LED package structure according to another embodiment of the invention.

FIG. 5B is a cross-sectional view of the LED package structure of FIG. 5A viewing along a line E-E.

FIG. 6A is a top view of an LED package structure according to another embodiment of the invention.

FIG. 6B is a cross-sectional view of the LED package structure of FIG. 6A viewing along a line F-F.

FIG. 7A is a top view of an LED package structure according to another embodiment of the invention.

FIG. 7B is a cross-sectional view of the LED package structure of FIG. 7A viewing along a line G-G.

FIG. 8A is a top view of an LED package structure according to another embodiment of the invention.

FIG. 8B is a cross-sectional view of the LED package structure of FIG. 8A viewing along a line H-H.

FIG. 9A is a top view of an LED package structure according to another embodiment of the invention.

FIG. 9B is a cross-sectional view of the LED package structure of FIG. 9A viewing along a line I-I.

FIG. 10A is a top view of an LED package structure according to another embodiment of the invention.

FIG. 10B is a cross-sectional view of the LED package structure of FIG. 10A viewing along a line J-J.

FIG. 11A is a top view of an LED package structure according to another embodiment of the invention.

FIG. 11B is a cross-sectional view of the LED package structure of FIG. 11A viewing along a line K-K.

FIG. 12A is a top view of an LED package structure according to another embodiment of the invention.

FIG. 12B is a cross-sectional view of the LED package structure of FIG. 12A bonded to a circuit board in a flip-chip manner and viewing along a line L-L.

FIG. 13 is a top view of an LED package structure according to another embodiment of the invention.

FIG. 14 is a cross-sectional view of an LED package structure according to another embodiment of the invention.

FIG. 15A is a top view of an LED package structure according to another embodiment of the invention.

FIG. 15B is a cross-sectional view of the LED package structure of FIG. 15A viewing along a line M-M.

FIG. 16A is a top view of an LED package structure according to another embodiment of the invention.

FIG. 16B is a cross-sectional view of the LED package structure of FIG. 16A viewing along a line N-N.

FIG. 17A is a top view of an LED package structure according to another embodiment of the invention.

FIG. 17B is a cross-sectional view of the LED package structure of FIG. 17A viewing along a line P-P.

FIG. 18A is a cross-sectional view of an LED package structure of FIG. 1B bonded to a circuit board through a flip-chip bonding manner.

FIG. 18B is a partial enlarged view of a region M1 in FIG. 18A.

DESCRIPTION OF EMBODIMENTS

FIG. 1A is a top view of a light emitting device according to an embodiment of the invention. FIG. 1B is a cross-sectional view of the light emitting device of FIG. 1A viewing along a line A-A. Referring to FIG. 1A and FIG. 1B, in the present embodiment, the light emitting device 100 a includes a light transmissive layer 110, a light emitting unit 120 a, and an encapsulant 130 a. The light emitting unit 120 a is, for example, a light emitting diode (LED), and includes a substrate 122, an epitaxial structure layer 124, a first electrode 126 a and a second electrode 128 a. The epitaxial structural layer 124 is disposed on the substrate 122. In the present embodiment, a periphery of the epitaxial structure layer 124 is aligned with a periphery of the substrate 122. The first electrode 126 a is disposed on one side of the epitaxial structure layer 124. The second electrode 128 a is disposed on the epitaxial structure layer 124, where the second electrode 128 a and the first electrode 126 a are located on the same side of the epitaxial structure layer 124 opposite to the substrate 122, and the first electrode 126 a and the second electrode 128 a have an interval d therebetween. The light emitting unit 120 a is disposed on the light transmissive layer 110, and the light transmissive layer 110 is located at one side of the substrate 122 of the light emitting unit 120 a that is opposite to the epitaxial structure layer 124, the first electrode 126 a and the second electrode 128 a, and at least exposes a part of the first electrode 126 a and a part of the second electrode 128 a. The encapsulant 130 a is disposed on the light transmissive layer 110, and is located between the light emitting unit 120 a and the light transmissive layer 110, where the encapsulant 120 a encapsulates the light emitting unit 120 a and exposes at least a part of the first electrode 126 a and a part of the second electrode 128 a, and the first electrode 126 a and the second electrode 128 a respectively extend outward from the epitaxial structure layer 124, and respectively cover at least a part of an upper surface 132 a of the encapsulant 130 a. In detail, the epitaxial structure layer 124 at least includes a first semiconductor layer (not shown), a light emitting layer (not shown) and a second semiconductor layer (not shown) electrically connected to each other in a sequence, where the first electrode 126 a is electrically connected to the first semiconductor layer, and the second electrode 128 a is electrically connected to the second semiconductor layer. In the present embodiment, an edge of the encapsulant 130 a is aligned with an edge of the light transmissive layer 110, such that the light emitting device 100 a has one or a plurality of flat surfaces.

In detail, the light transmissive layer 110 of the present embodiment is adapted to guide the light emitted by the light emitting unit 120 a and is pervious to the light, where a material of the light transmissive layer 110 is, for example, a transparent inorganic material, which includes but is not limited to glass or ceramic; or a transparent organic material, which includes but is not limited to silicone, epoxy resin, or various resins, and a light transmittance of the light transmissive layer 110 is at least 50%, preferably. A pattern of the light transmissive layer 110 can be a flat light transmissive plate or a light transmissive layer with other shapes. In other embodiments of the invention, the light emitting device 100 a may not include the light transmissive layer 110, and the encapsulant 130 a has one or a plurality of flat surfaces. The light emitting unit 120 a is, for example, a flip-chip LED chip, where a material of the substrate 122 of the light emitting unit 120 a is, for example, sapphire, gallium nitride, gallium oxide, silicon carbide or zinc oxide, though the invention is not limited thereto. Moreover, the first electrode 126 a of the present embodiment includes a first electrode portion 126 a 1 and a first electrode extending portion 126 a 2. The second electrode 128 a includes a second electrode portion 128 a 1 and a second electrode extending portion 128 a 2. Edges of the first electrode portion 126 a 1 and the second electrode portion 128 a 1 are aligned with or not aligned with (for example, contracted inward relative to) the edge of the epitaxial structure layer 124. The first electrode extending portion 126 a 2 is located on the first electrode portion 126 a 1, and extends outward to cover the upper surface 132 a of the encapsulant 130 a. The second electrode extending portion 128 a 2 is located on the second electrode portion 128 a 1, and extends outward to cover the upper surface 132 a of the encapsulant 130 a. Here, the first electrode portion 126 a 1 and the first electrode extending portion 126 a 2 may adopt the same material or different materials, and the second electrode portion 128 a 1 and the second electrode extending portion 128 a 2 may also adopt the same material or different materials, which is not limited by the invention. In the present embodiment, the first electrode extending portion 126 a 2 respectively extends upward from the first electrode portion 126 a 1 and extends along a direction away from the second electrode portion 128 a 1, and the second electrode extending portion 128 a 2 respectively extends upward from the second electrode portion 128 a 1 and extends along a direction away from the first electrode portion 126 a 1.

Moreover, a material of the encapsulant 130 a is, for example, a transparent inorganic material or organic material, where the inorganic material includes but is not limited to glass or ceramic, and the organic material includes but is not limited to silicone, epoxy resin, or various resins. The light emitting device 100 a further includes at least one wavelength conversion material, where the wavelength conversion material includes but is not limited to a fluorescent material or a quantum dot material. The wavelength conversion material 134 a can be doped in the encapsulant 130 a for changing a wavelength of the light emitted by the light emitting unit 120 a. In other embodiments of the invention, a wavelength conversion material layer can be directly formed on a surface of the light emitting unit 120 a, and at least a part of the first electrode 126 a and a part of the second electrode 128 a are exposed, and the wavelength conversion material layer is located between the encapsulant 130 a and the light emitting unit 120 a, and a method for forming the wavelength conversion material layer includes but is not limited to spray coating or adhering. In another embodiment of the invention, the wavelength conversion material layer can be formed on the surface of the encapsulant 130 a, and at least a part of the first electrode 126 a and a part of the second electrode 128 a are exposed, and the encapsulant 130 a is located between the wavelength conversion material layer and the light emitting unit 120 a, and a method for forming the wavelength conversion material layer includes but is not limited to spray coating or adhering. Certainly, in other embodiments, the light emitting device 100 a may not include the wavelength conversion material, which is still a technical scheme adopted by the invention without departing from the protection range of the invention.

In brief, since the first electrode 126 a and the second electrode 128 a of the present embodiment have the first electrode extending portion 126 a 2 and the second electrode extending portion 128 a 2 covering the upper surface 132 a of the encapsulant 130 a, compared to the conventional design of the first electrode and the second electrode, the light emitting device 100 a (for example, the LED package) of the present embodiment has a larger electrode area. Moreover, when the LED package 100 a is to be assembled to an external circuit (not shown), the design of the first electrode 126 a and the second electrode 128 a avails improving the alignment accuracy of the LED package in assembling and avoiding a conventional problem of poor electrode contact. To be specific, since the first electrode extending portion 126 a 2 and the second electrode extending portion 128 a 2 respectively enlarge the areas of the first electrode portion 126 a 1 and the second electrode portion 128 a 1, when the first electrode 126 a and the second electrode 128 a are respectively bonded to a circuit board through a solder paste, conductive bumps or other conductive connection material, due to overflow of the conductive connection material (for example, the solder paste), the solder paste on the first electrode 126 a and the solder paste on the second electrode 128 a are contacted to cause a short circuit. Therefore, by adopting the first electrode extending portion 126 a 2 and the second electrode extending portion 128 a 2 of the present embodiment, the light emitting device 100 a has a larger electrode area, so that when the light emitting device 100 a is bonded to the circuit board through the solder paste, the situation of short circuit caused by overflow of the solder paste is mitigated or avoided, so as to ensure bonding reliability.

It should be noticed that in the present embodiment, an edge of the first electrode extending portion 126 a 2 and an edge of the second electrode extending portion 128 a 2 are aligned with an edge of the encapsulant 130 a and an edge of the light transmissive layer 110, besides that the electrode area is enlarged to increase the alignment accuracy, such design can be more simple in a manufacturing process, so as to save a manufacturing time, and a reason thereof is that the encapsulant 130 a can encapsulate a plurality of the light emitting units 120 a having the first electrode portion 126 a 1 and the second electrode portion 128 a 1 in one process, and after the first electrode extending portion 126 a 2 and the second electrode extending portion 128 a 2 are simultaneously plated, a cutting process is performed to form the light emitting device 100 a (for example, the LED package structure).

It should be noticed that reference numbers of the components and a part of contents of the aforementioned embodiment are also used in the following embodiment, wherein the same reference numbers denote the same or like components, and descriptions of the same technical contents are omitted. The aforementioned embodiment can be referred for descriptions of the omitted parts, and detailed descriptions thereof are not repeated in the following embodiment.

FIG. 2A is a top view of a light emitting device according to another embodiment of the invention. FIG. 2B is a cross-sectional view of the light emitting device of FIG. 2A viewing along a line B-B. Referring to FIG. 2A and FIG. 2B, the light emitting device 100 b of the present embodiment is similar to the light emitting device 100 a of FIG. 1A and FIG. 1B, and a main difference therebetween is that the first electrode extending portion 126 b 2 of the first electrode 126 b is composed of a plurality of first grating type electrodes R1, and the second electrode extending portion 128 b 2 of the second electrode 128 b is composed of a plurality of second grating type electrodes R2. A part of the first grating type electrodes R1 and a part of the second grating type electrodes R2 respectively extend upward from the first electrode portion 126 b 1 and the second electrode portion 128 b 1, and a part of the first grating type electrodes R1 and a part of the second grating type electrodes R2 are disposed on the upper surface 132 a of the encapsulant 130 a.

The first grating type electrodes R1 are arranged in intervals (for example, equally spaced) and expose a part of the first electrode portion 126 b 1 and a part of the encapsulant 130 a. The second grating type electrodes R2 are arranged in intervals (for example, equally spaced) and expose a part of the second electrode portion 128 b 1 and a part of the encapsulant 130 a. Particularly, each of the first grating type electrodes R1 has a first top surface T1, and each of the second grating type electrodes R2 has a second top surface T2. The first top surfaces T1 of the first gating type electrodes R1 and the second top surfaces T2 of the second grating type electrodes R2 are substantially coplanar. In this way, when the light emitting device 100 b is subsequently assembled to an external circuit (not shown), the design of the first electrode 126 a and the second electrode 128 b of the light emitting unit 120 b can provide a good assembling flatness and a larger electrode area to facilitate subsequent assembling of the LED package structure 100 b.

FIG. 3A is a top view of a light emitting device according to another embodiment of the invention. FIG. 3B is a cross-sectional view of the light emitting device of FIG. 3A viewing along a line C-C. Referring to FIG. 3A and FIG. 3B, the light emitting device 100 c of the present embodiment is similar to the light emitting device 100 b of FIG. 2A and FIG. 2B, and a main difference therebetween is that the first electrode extending portion 126 c 2 of the present embodiment is composed of a plurality of first grating type electrodes R1′, and the second electrode extending portion 128 c 2 is composed of a plurality of second grating type electrodes R2′, where the first grating type electrodes R1′ and the second grating type electrodes R2′ are further disposed at the interval d between the first electrode 126 c and the second electrode 128 c. In this way, the electrode area of the light emitting unit 120 c can extend to the encapsulant 130 a from the epitaxial structure layer 124, such that the light emitting device 100 c has a larger electrode area to achieve a simple manufacturing process, and avail improving the alignment accuracy of subsequent assembling process. It should be noticed that the connection between the grating type electrodes and the circuit board can be implemented through an anisotropic conductive adhesive.

FIG. 4A is a top view of a light emitting device according to another embodiment of the invention. FIG. 4B is a cross-sectional view of the light emitting device of FIG. 4A viewing along a line D-D. Referring to FIG. 4A and FIG. 4B, the light emitting device 100 d of the present embodiment is similar to the light emitting device 100 a of FIG. 1A and FIG. 1B, and a main difference therebetween is that the encapsulant 130 d of the present embodiment further wraps the first electrode 126 d and the second electrode 128 d and exposes the upper surfaces of the above electrodes, and the encapsulant 130 d fills up the interval d between the first electrode 126 d and the second electrode 128 d, where a sidewall of the first electrode extending portion 126 d 2 and a sidewall of the second electrode extending portion 128 d 2 are also wrapped by the encapsulant 130 d. Moreover, the edge of the first electrode extending portion 126 d 2 and the edge of the second electrode extending portion 128 d 2 are contracted relative to the edge of the encapsulant 130 d and the edge of the light transmissive layer 110. A first upper surface Si of the first electrode extending portion 126 d 2 and a second upper surface S2 of the second electrode extending portion 128 d 2 are substantially coplanar with the upper surface 132 d of the encapsulant 130 d. Namely, the first electrode extending portion 126 d 2 is disposed on the first electrode portion 126 d 1, and the first upper surface Si of the first electrode extending portion 126 d 2 is substantially coplanar with the upper surface 132 d of the encapsulant 130 d. The second electrode extending portion 128 d 2 is disposed on the second electrode portion 128 d 1, and the second upper surface S2 of the second electrode extending portion 128 d 2 is substantially coplanar with the upper surface 132 d of the encapsulant 130 d. In this way, when the light emitting device 100 d is electrically connected to an external circuit (not shown), the design of the first electrode 126 d and the second electrode 128 d of the light emitting unit 120 d results in a fact that the light emitting device 100 d has no assembling gap in assembling, so as to effectively prevent moisture and oxygen from entering the light emitting device 100 d.

FIG. 5A is a top view of a light emitting device according to another embodiment of the invention. FIG. 5B is a cross-sectional view of the light emitting device of FIG. 5A viewing along a line E-E. Referring to FIG. 5A and FIG. 5B, the light emitting device 100 e of the present embodiment is similar to the light emitting device 100 d of FIG. 4A and FIG. 4B, and a main difference therebetween is that the first electrode extending portion 126 e 2 and the first electrode portion 126 e 1 of the present embodiment have a seamless connection therebetween, and the second electrode extending portion 128 e 2 and the second electrode portion 128 e 1 have a seamless connection therebetween. Namely, the first electrode extending portion 126 e 2 and the first electrode portion 126 e 1 of the first electrode 126 e of the light emitting unit 120 e are formed integrally, and the second electrode extending portion 128 e 2 and the second electrode portion 128 e 1 of the second electrode 128 e are formed integrally, such that integrity of the light emitting device 100 e is better so as to achieve better reliability.

FIG. 6A is a top view of a light emitting device according to another embodiment of the invention. FIG. 6B is a cross-sectional view of the light emitting device of FIG. 6A viewing along a line F-F. Referring to FIG. 6A and FIG. 6B, the light emitting device 100 f of the present embodiment is similar to the light emitting device 100 d of FIG. 4A and FIG. 4B, and a main difference therebetween is that the edge of the first electrode extending portion 126 f 2 and the edge of the second electrode extending portion 128 f 2 are aligned with the edge of the encapsulant 130 f and the edge of the light transmissive unit 110, and are not wrapped by the encapsulant 130 f. Now, the first electrode extending portion 126 f 2 of the light emitting unit 120 f is disposed on the first electrode portion 126 f 1, and the first upper surface S1′ of the first electrode extending portion 126 f 2 is substantially coplanar with the upper surface 132 f of the encapsulant 130 f. The second electrode extending portion 128 f 2 of the light emitting unit 120 f is disposed on the second electrode portion 128 f 1, and the second upper surface S2′ of the second electrode extending portion 128 f 2 is substantially coplanar with the upper surface 132 f of the encapsulant 130 f.

FIG. 7A is a top view of a light emitting device according to another embodiment of the invention. FIG. 7B is a cross-sectional view of the light emitting device of FIG. 7A viewing along a line G-G. Referring to FIG. 7A and FIG. 7B, the light emitting device 100 g of the present embodiment is similar to the light emitting device 100 f of FIG. 6A and FIG. 6B, and a main difference therebetween is that the first electrode extending portion 126 g 2 and the first electrode portion 126 g 1 of the present embodiment have a seamless connection therebetween, and the second electrode extending portion 128 g 2 and the second electrode portion 128 g 1 have a seamless connection therebetween. Namely, the first electrode extending portion 126 g 2 and the first electrode portion 126 g 1 of the first electrode 126 g of the light emitting unit 120 g are formed integrally, and the second electrode extending portion 128 g 2 and the second electrode portion 128 g 1 of the second electrode 128 g are formed integrally.

FIG. 8A is a top view of a light emitting device according to another embodiment of the invention. FIG. 8B is a cross-sectional view of the light emitting device of FIG. 8A viewing along a line H-H. Referring to FIG. 8A and FIG. 8B, the light emitting device 100 h of the present embodiment is similar to the light emitting device 100 g of FIG. 7A and FIG. 7B, and a main difference therebetween is that the first electrode 126 h of the light emitting unit 120 h of the present embodiment further includes a first connection portion 126 h 3 connecting the first electrode portion 126 h 1 and the first electrode extending portion 126 h 2. An extending direction of the first connection portion 126 h 3 is perpendicular to an extending direction of the first electrode portion 126 h 1 and an extending direction of the first electrode extending portion 126 h 2. The first electrode portion 126 h 1, the first connection portion 126 h 3 and the first electrode extending portion 126 h 2 may have a seamless connection therebetween. The second electrode 128 h of the light emitting unit 120 h further includes a second connection portion 128 h 3 connecting the second electrode portion 128 h 1 and the second electrode extending portion 128 h 2. An extending direction of the second connection portion 128 h 3 is perpendicular to an extending direction of the second electrode portion 128 h 1 and an extending direction of the second electrode extending portion 128 h 2. The second electrode portion 128 h 1, the second connection portion 128 h 3 and the second electrode extending portion 128 h 2 may have a seamless connection therebetween. The first upper surface S1″ of the first electrode extending portion 126 h 2 and the second upper surface S2″ of the second electrode extending portion 128 h 2 are substantially coplanar with the upper surface 132 h of the encapsulant 130 h. The encapsulant 130 h fills up the interval d between the first electrode 126 h and the second electrode 128 h. The edge of the first electrode extending portion 126 h 2 and the edge of the second electrode extending portion 128 h 2 are aligned with the edge of the encapsulant 130 h and the edge of the light transmissive layer 110.

FIG. 9A is a top view of a light emitting device according to another embodiment of the invention. FIG. 9B is a cross-sectional view of the light emitting device of FIG. 9A viewing along a line I-I. Referring to FIG. 9A and FIG. 9B, the light emitting device 100 i of the present embodiment is similar to the light emitting device 100 h of FIG. 8A and FIG. 8B, and a main difference therebetween is that the sidewall of the first electrode extending portion 126 i 2 and the sidewall of the second electrode extending portion 128 i 2 are wrapped by the encapsulant 130 i in this embodiment. Namely, the first electrode 126 i, the second electrode 128 i, the epitaxial structure layer 124 and the substrate 122 of the light emitting unit 120 i are encapsulated by the encapsulant 130 i, though the upper surfaces of the above electrodes are exposed. The first electrode extending portion 126 i 2 of the first electrode 126 i is connected to the first electrode portion 126 i 1 through the first connection portion 126 i 3, and the first surface S1″ of the first electrode extending portion 126 i 2 is substantially coplanar with the upper surface 132 i of the encapsulant 130 i. Moreover, the second electrode extending portion 128 i 2 of the second electrode 128 i is connected to the second electrode portion 128 i 1 through the second connection portion 128 i 3, and the second surface S2′″ of the second electrode extending portion 128 i 2 is substantially coplanar with the upper surface 132 i of the encapsulant 130 i.

FIG. 10A is a top view of a light emitting device (LED package) according to another embodiment of the invention. FIG. 10B is a cross-sectional view of the light emitting device of FIG. 10A viewing along a line J-J. Referring to FIG. 10A and FIG. 10B, the light emitting device (LED package) 100 j of the present embodiment is similar to the light emitting device 100 a of FIG. 1A, and differences therebetween are as follows. In the LED package 100 j of the present embodiment, the first electrode extending portion 126 j 2 includes a plurality of first sub-electrodes 126 j 21, 126 j 22 separated from each other, and the second electrode extending portion 128 j 2 includes a plurality of second sub-electrodes 128 j 21, 128 j 22 separated from each other. In the present embodiment, the first sub-electrodes 126 j 21, 126 j 22 are located at two adjacent corners of the encapsulant, and the second sub-electrodes 128 j 21, 128 j 22 are located at the other two adjacent corners of the encapsulant. In other words, the first sub-electrodes 126 j 21, 126 j 22 extend from the edge of the first electrode portion 126 j 1 along a direction away from the second electrode portion 128 j 1, and the second sub-electrodes 128 j 21, 128 j 22 extend from the edge of the second electrode portion 128 j 1 along a direction away from the first electrode portion 126 j 1, so that the sub-electrodes 126 j 21, 126 j 22, 128 j 21, 128 j 22 respectively extend to four corners of the supper surface of the light emitting device 100 j. Moreover, in the present embodiment, the encapsulant 130 j encapsulates the first electrode portion 126 j 1 and the second electrode portion 128 j 1, and the sub-electrodes 126 j 21, 126 j 22, 128 j 21 and 128 j 22 extend to cover the encapsulant 130 j. In the present embodiment, the LED package 100 j may further include a light transmissive layer 110, and the encapsulant 130 j is disposed on the light transmissive layer 110. Compared to FIG. 1B, FIG. 10B only illustrates a situation that the LED package 100 j is turned off to facilitate flip-chip bonding.

In the LED package 100 j of the present embodiment, since the sub-electrodes 126 j 21, 126 j 22, 128 j 21, 128 j 22 configured at the four corners of the upper surface of the LED package 100 j can be respectively bonded to the circuit board through four solder pastes, and the four solder pastes configured at the four corners can disperse a stress in case of reflow. In this way, after the LED package 100 j is bonded to the circuit board and cooled down, the LED package 100 j is avoid to be shifted by an angle relative to a predetermined position, so as to ensure a yield of the bonding process.

FIG. 11A is a top view of an LED package according to another embodiment of the invention. FIG. 11B is a cross-sectional view of the LED package of FIG. 11A viewing along a line K-K. Referring to FIG. 11A and FIG. 11B, the LED package 100 k of the present embodiment is similar to the LED package 100 j of FIG. 10A and FIG. 10B, and differences therebetween are as follows. In the LED package 100 k of the present embodiment, the areas that the first sub-electrodes 126 k 21, 126 k 22 of the first electrode extending portion 126 k 2 respectively cover the first electrode portion 126 k 1 are relatively small, and the first sub-electrodes 126 k 21, 126 k 22 respectively cover two adjacent corners of the first electrode portion 126 k 1, where the two adjacent corners are respectively close to the two adjacent corners of the upper surface of the LED package 100 k. Moreover, the areas that the second sub-electrodes 128 k 21, 128 k 22 of the second electrode extending portion 128 k 2 respectively cover the second electrode portion 128 k 1 are relatively small, and the second sub-electrodes 128 k 21, 128 k 22 respectively cover two adjacent corners of the second electrode portion 128 k 1, where the two adjacent corners are respectively close to the two adjacent corners of the upper surface of the LED package 100 k.

FIG. 12A is a top view of an LED package according to another embodiment of the invention. FIG. 12B is a cross-sectional view of the LED package of FIG. 12A bonded to a circuit board in a flip-chip manner and viewing along a line L-L. Referring to FIG. 12A and FIG. 12B, the LED package 1001 of the present embodiment is similar to the LED package 100 k of FIG. 11A and FIG. 11B, and differences therebetween are as follows. In the LED package 1001 of the present embodiment, the first sub-electrodes 126 l 21-126 l 28 of the first electrode extending portion 126 l 2 are grouped into two first sub-electrode groups 1261 a and 1261 b, where each of the first sub-electrode groups 1261 a and 1261 b respectively includes a part of the first sub-electrodes. For example, as shown in FIG. 12A, the first sub-electrode group 1261 a includes four first sub-electrodes 126 l 21-126 l 24, and the first sub-electrode group 1261 b includes four first sub-electrodes 126 l 25-126 l 28. Moreover, the second sub-electrodes 128 l 21-128 l 28 of the second electrode extending portion 128 l 2 are grouped into two second sub-electrode groups 1281 a and 1281 b, where each of the second sub-electrode groups 1281 a and 1281 b respectively includes a part of the second sub-electrodes. For example, as shown in FIG. 12A, the second sub-electrode group 1281 a includes four second sub-electrodes 128 l 21-128 l 24, and the second sub-electrode group 1281 b includes four second sub-electrodes 128 l 25-128 l 28. In the present embodiment, the two first sub-electrode groups 1261 a and 1261 b are respectively disposed at two adjacent corners on the upper surface of the LED package 1001, and the two second sub-electrode groups 1281 a and 1281 b are respectively disposed at the other two adjacent corners on the upper surface of the LED package 1001.

The light emitting device 1001 can be bonded to the circuit board 50 through the flip-chip bonding manner. For example, the two first sub-electrode groups 1261 a, 1261 b are respectively bonded to electrode pads 52 (for example, the electrode pads 52 located to the left as shown in FIG. 12B) on the circuit board 50 through two cured solder pastes 60, and the two second sub-electrode groups 1281 a, 1281 b are respectively bonded to electrode pads 52 (for example, the electrode pads 52 located to the right as shown in FIG. 12B) on the circuit board 50 through two cured solder pastes 60. Since the solder pastes 60 can be filled in an interval between two adjacent sub-electrodes before curing, a bonding force between the solder pastes 60 and the first sub-electrodes 126 l 21-126 l 28 and a bonding force between the solder pastes 60 and the second sub-electrodes 128 l 21-128 l 28 can be effectively enhanced, so as to improve reliability of the light emitting device 1001 bonded to the circuit board 50.

FIG. 13 is a top view of a light emitting device according to another embodiment of the invention. Referring to FIG. 13, the light emitting device 100 m of the present embodiment is similar to the light emitting device 100 j of FIG. 10A, and differences therebetween are as follows. In the light emitting device 100 m of the present embodiment, the first sub-electrodes 126 m 21, 126 m 23 of the first electrode extending portion 126 m 2 are respectively disposed at two adjacent corners on the upper surface of the light emitting device 100 m, and the first sub-electrode 126 m 22 is disposed between the first sub-electrode 126 m 21 and the first sub-electrode 126 m 23. Moreover, the second sub-electrodes 128 m 21, 128 m 23 of the second electrode extending portion 128 m 2 are respectively disposed at another two adjacent corners on the upper surface of the light emitting device 100 m, and the second sub-electrode 128 m 22 is disposed between the second sub-electrode 128 m 21 and the second sub-electrode 128 m 23.

In other embodiments of the invention, the number and configuration of the first sub-electrodes and the second sub-electrodes can be modified, which is not limited by the invention.

FIG. 14 is a cross-sectional view of a light emitting device according to another embodiment of the invention. Referring to FIG. 14, the light emitting device 100 n of the present embodiment is similar to the light emitting device 100 a of FIG. 1B, and differences therebetween are as follows. In the present embodiment, the light emitting device 100 n further includes a reflection layer 140 n, which is at least disposed on the upper surface 132 a of the encapsulant 130 a. In the present embodiment, at least a part of the reflection layer 140 n is disposed between the first electrode 126 a and the upper surface 132 a of the encapsulant 130 a, and between the second electrode 128 a and the upper surface 132 a of the encapsulant 130 a. To be specific, the reflection layer 140 n can be disposed between the first electrode extending portion 126 a 2 and the upper surface 132 a of the encapsulant 130 a and between the second electrode extending portion 128 a 2 and the upper surface 132 a of the encapsulant 130 a. The reflection layer 140 a is, for example, gold, aluminium, silver, nickel, titanium, distributed Bragg reflector (DBR), a resin layer doped with reflection particles with high reflectivity (for example, a silicone layer or an epoxy resin layer) or a combination thereof. The reflection layer 140 n can reflect the light emitted by the light emitting unit 120 a to the light transmissive layer 110, such that the light can effectively emit out from the light transmissive layer 110. When the reflection layer 140 n is made of an insulation material, the reflection layer 140 n can be connected in a whole piece to cover the entire upper surface 132 a of the encapsulant 130 a. However, when the reflection layer 140 n is made of a conductive material or a metal material, the part of the reflection layer 140 n disposed under the first electrode extending portion 126 a 2 has to be separated from the part of the reflection layer 140 n disposed under the second electrode extending portion 128 a 2 to avoid short circuit.

FIG. 15A is a top view of a light emitting device according to another embodiment of the invention. FIG. 15B is a cross-sectional view of the light emitting device of FIG. 15A viewing along a line M-M. Referring to FIG. 15A and FIG. 15B, the light emitting device 100 p of the present embodiment is similar to the light emitting device 100 f of FIG. 6A and FIG. 6B, and differences therebetween are as follows. In the light emitting device 100 p of the present embodiment, the first electrode 126 p and the second electrode 128 p extend upward from the epitaxial structure layer 124 to protrude out from the upper surface 132 a of the encapsulant 130 a. In the present embodiment, neither the first electrode 126 p nor the second electrode 128 p covers the upper surface 132 a of the encapsulant 130 a.

To be specific, the first electrode extending portion 126 p 2 of the first electrode 126 p is disposed on the first electrode portion 126 a 1 and protrudes out from the upper surface 132 a of the encapsulant 130 a, and the second electrode extending portion 128 p 2 of the second electrode 128 p is disposed on the second electrode portion 128 a 1 and protrudes out from the upper surface 132 a of the encapsulant 130 a. In the present embodiment, neither the first electrode extending portion 126 p 2 nor the second electrode extending portion 128 p 2 covers the upper surface 132 a of the encapsulant 130 a, and the first electrode extending portion 126 p 2 and the second electrode extending portion 128 p 2 are substantially coplanar. In another embodiment, the first electrode 126 p and the second electrode 128 p can also extend upward from the epitaxial structure layer 124 without protruding out from the upper surface 132 a of the encapsulant 130 a. For example, the upper surface of the first electrode extending portion 126 p 2 (i.e. the surface facing away from the epitaxial structure layer 124), the upper surface of the second electrode extending portion 128 p 2 (i.e. the surface facing away from the epitaxial structure layer 124) and the upper surface 132 a of the encapsulant 130 a are substantially coplanar.

In the present embodiment, by increasing heights of the first electrode 126 p and the second electrode 128 p through the first electrode extending portion 126 p 2 and the second electrode extending portion 128 p 2, it avails a follow-up chip bonding process.

FIG. 16A is a top view of a light emitting device according to another embodiment of the invention. FIG. 16B is a cross-sectional view of the light emitting device viewing along a line N-N of FIG. 16A. Referring to FIG. 16A and FIG. 16B, the light emitting device 100 q of the present embodiment is similar to the light emitting device 100 p of FIG. 15A and FIG. 15B, and differences therebetween are as follows. In the light emitting device 100 q of the present embodiment, the first electrode extending portion extending upward includes a plurality of first sub-electrodes 126 q 2 separated from each other, and the second electrode extending portion extending upward includes a plurality of second sub-electrodes 128 q 2 separated from each other.

FIG. 17A is a top view of a light emitting device according to another embodiment of the invention. FIG. 17B is a cross-sectional view of the light emitting device of FIG. 17A viewing along a line P-P. Referring to FIG. 17A and FIG. 17B, the light emitting device 100 r of the present embodiment is similar to the light emitting device 100 q of FIG. 16A and FIG. 16B, and a main difference therebetween is that the first sub-electrodes 126 q 2 and the second sub-electrodes 128 q 2 of the light emitting device 100 q are laminar electrodes, and the first sub-electrodes 126 r 2 and the second sub-electrodes 128 r 2 of the light emitting device 100 r of the present embodiment are spherical electrodes, which can be formed according to a ball planting technique.

FIG. 18A is a cross-sectional view of a light emitting device of FIG. 1B bonded to a circuit board through a flip-chip bonding manner. FIG. 18B is a partial enlarged view of a region M1 in FIG. 18A. Referring to FIG. 18A and FIG. 18B, the light emitting device 100 a can be bonded to the circuit board 50 through the flip-chip bonding manner. For example, the first electrode extending portion 126 a 2 and the second electrode extending portion 128 a 2 are respectively bonded to the two electrode pads 52 on the circuit board 50 through two cured solder pastes 60.

In the present embodiment, the first electrode extending portion 126 a 2 and the second electrode extending portion 128 a 2 respectively include an adhesion layer L1 and a barrier layer L2 disposed between the adhesion layer L1 and the encapsulant 130 a. A material of the adhesion layer L1 includes gold, tin, aluminium, silver, copper, indium, bismuth, platinum, gold-tin alloy, tin-silver alloy, tin-silver-copper alloy (Sn—Ag—Cu (SAC) alloy) or a combination thereof, and a material of the barrier layer L2 includes nickel, titanium, tungsten, gold or an alloy of a combination thereof. The adhesion layer L1 is easy to be bonded with the solder pastes 60, and the barrier layer L2 can effectively prevent the material of the solder pastes 60 from invading the encapsulant 130 a to contaminate the light emitting device 100 a during the bonding process.

In the present embodiment, the first electrode extending portion 126 a 2 and the second electrode extending portion 128 a 2 further respectively include a reflection layer L3, which is at least disposed between the barrier layer L2 and the encapsulant 130 a. The reflection layer L3 can reflect the light coming from the epitaxial structure layer 124 to improve a light usage rate. In the present embodiment, a material of the reflection layer L3 includes gold, aluminium, silver, nickel, titanium or an alloy of a combination thereof.

In summary, the first electrode and the second electrode of the light emitting unit according to the embodiment of the invention extend outward from the epitaxial structure layer to cover the encapsulant, namely, the light emitting device of the invention has a larger electrode area, so that when the light emitting device is to be assembled to an external circuit, the alignment accuracy of assembling is effectively improved. Since the first electrode and the second electrode of the light emitting unit according to the embodiment of the invention extend upward from the epitaxial structure layer, and protrude out of the encapsulant, it avails a follow-up chip bonding process.

It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents. 

What is claimed is:
 1. A light emitting device, comprising: a light emitting unit, comprising: a substrate, an epitaxial structure layer, disposed on the substrate; and a first electrode and a second electrode, respectively disposed on a same side of the epitaxial structure layer opposite to the substrate; and an encapsulant encapsulating the light emitting unit and at least exposing a part of the first electrode and a part of the second electrode, wherein the first electrode and the second electrode extend outwardly to protrude from a lower surface of the encapsulant respectively; wherein the first electrode comprises a first electrode portion connected to the epitaxial structure layer and a first electrode extending portion connected to the first electrode portion, the second electrode comprises a second electrode portion connected to the epitaxial structure layer and a second electrode extending portion connected to the second electrode portion, wherein the first electrode extending portion and the second electrode extending portion respectively comprise an adhesion layer and a barrier layer disposed between the adhesion layer and the epitaxial structure layer.
 2. The light emitting device as claimed in claim 1, wherein a material of the adhesion layer comprises gold, tin, aluminium, silver, copper, indium, bismuth, platinum, gold-tin alloy, tin-silver alloy, tin-silver-copper alloy (Sn—Ag—Cu (SAC) alloy) or a combination thereof, and a material of the barrier layer includes nickel, titanium, tungsten, gold or an alloy of a combination thereof.
 3. The light emitting device as claimed in claim 2, wherein the first electrode extending portion and the second electrode extending portion respectively comprise a reflection layer disposed between the barrier layer and the epitaxial structure layer.
 4. The light emitting device as claimed in claim 3, wherein a material of the reflection layer comprises gold, aluminium, silver, nickel, titanium, or an alloy of a combination thereof.
 5. A light emitting device, comprising: a light emitting unit, comprising: a substrate, an epitaxial structure layer, disposed on the substrate; and a first electrode and a second electrode, respectively disposed on a same side of the epitaxial structure layer opposite to the substrate; and an encapsulant encapsulating the light emitting unit and at least exposing a part of the first electrode and a part of the second electrode, wherein the first electrode and the second electrode extend outwardly to protrude from a lower surface of the encapsulant respectively; wherein the first electrode and the second electrode respectively comprise an adhesion layer, a reflection layer and a barrier layer disposed between the adhesion layer and the reflection layer, and the reflection layer is disposed between the barrier layer and the epitaxial structure layer.
 6. The light emitting device as claimed in claim 5, wherein a material of the adhesion layer comprises gold, tin, aluminium, silver, copper, indium, bismuth, platinum, gold-tin alloy, tin-silver alloy, tin-silver-copper alloy (Sn—Ag—Cu (SAC) alloy) or a combination thereof, and a material of the barrier layer includes nickel, titanium, tungsten, gold or an alloy of a combination thereof.
 7. The light emitting device as claimed in claim 5, wherein a material of the reflection layer comprises gold, aluminium, silver, nickel, titanium, or an alloy of a combination thereof. 